20 EXPERIMENT STATION RECORD. 



growth of higher plants, generally understood to require a soil rich in mineral 

 nutrients." 



The soils are different from European moor soils in containing a much higher 

 percentage of nitrogen at all depths, being richest in the top layer, and in having 

 a higher percentage of ash in the upland soils than in the low bogs. 



The method used in analyzing the soils is described. 



The effect of moisture and of solutions upon the electric conductivity of 

 soils, R. O. E. Davis (Trans. Anier. Electrochem. Soc, 11 {1910), i)p. 391-403, 

 figs. 15.) — In this paper the author reports data on the following: (1) The 

 resistivity of different soil types, both air-dried and saturated; (2) the 

 resistivity and conductivity of soils for different percentages of water from 10 

 to 20 ; (3) the conductivity of solutions in the soil ; and (4) the eft"ect of texture 

 and organic matter, or humus, upon the conductivitj^ 



"The measurements of soil resistivity show: (1) That in the dry condition, 

 the soil offers a very high resistance to the passage of the current; (2) that at 

 a depth of 2 ft. or more for a given soil and area, the conductivity remains 

 roughly constant; (3) that the conductivity of moist soil increases almost 

 directly as the percentage of moisture increases, the amount of increase depend- 

 ing upon the type of soil; (4) that the conductivity of soils saturated with 

 water increases directly as the amount of salt in solution increases; (5) that 

 below saturation, the resistivity increases almost in proportion to the surface 

 area of the soil ; at saturation and beyond, the surface area does not exert so 

 great an influence; (6) that sodium carbonate has an effect of greatly increas- 

 ing the conductivity: (7) that humus decreases the conductivity of a soil; (8) 

 sandy soil will probably afford least electrolyte and clay soil most, due mostly 

 to the state of physical division of the soil." 



The author is of the opinion that from the data given " it would be possible 

 to calculate roughly the electrolysis (current passing) produced by a given 

 potential difference between two points in the soil, the cross-section of the soil 

 column involved being known. In such a calculation the texture, content of 

 organic matter, water content, and saturation point of the soil must be approxi- 

 mately known, as well as the content of soluble salts present in the soil 

 solution." 



Data on the chemical composition of alkali soils, N. Stepanov (Zliur. 

 Opuitn. Agron. {Russ. Jour. Expt. Landic), 11 (1910), No. 1, pp. 52-75). — 

 Analyses were made of extracts with hydrofluoric acid, sulphuric acid, 10 per 

 cent hot hydrochloric acid, 1 per cent cold hydrochloric acid, and water from 

 loamy chernozem and black alkali soils from Samara. 



In all acid extracts a marked increase in sesquioxids, magnesia, and alkalis, 

 especially sodium, was noted in the surface layer of the alkali soils. The 

 aqueous extracts of the alkali soils also showed a high sodium content in com- 

 parison with the chernozem soils. The characteristics of the aqueous alkali 

 extracts were difficulty of clarification, intensity of color (being that of strong 

 tea), high state of alkalinity, and very small content of lime, sulphuric acid, 

 and chlorin. The alkalinity decreased with the increase of sulphuric acid, a 

 fact confirmed in a plat experiment with gypsum. The mechanical analysis 

 showed a marked increase of fine soil particles in the surface layers of the 

 alkali soil. 



Experiments in wide glass tubes on the rise of water in the alkali soil 

 showed that the water rose only 55.2 cm. in 155 days. 



Chemistry, physics, and biology of the soil. M. Hoffmann (Jahresber. 

 Landw., 24 (1909), pp. 7-50). — Recent investigations on this subject are classi- 

 fied and reviewed. 



